Study shows right sugar levels for diabetics

05 August 2015

Damage to the eyes and kidneys are serious complications in diabetes, and the risk increases with rising blood sugar levels. After following one specific patient group for more than 20 years after the onset of diabetes, researchers at Linköping University are able to show what levels should be targeted during treatment.

The findings of the “VISS study” (Vascular diabetic complications in southeast Sweden) led by Professor Hans Arnqvist in collaboration with Professor Johnny Ludvigsson, is now being published in the current edition of the journal Diabetes Care with university chief physician Maria Nordwall as lead author.

The conclusion is that people with Type 1 diabetes do not suffer any serious eye or kidney damage if the value of the HbA1c blood test is below 60mmol/mol (7.6% NGSP).

Controlling blood sugar levelsDiabetes is the most common cause of blindness among adults, and of renal failure requiring dialysis or transplant. It is well known how regulating blood sugar is important for complications in diabetes, but just what treatment targets should be set has been uncertain.

The goal of the VISS study was investigating how blood sugar levels measured as HbA1c impacts the risk of developing serious eye or kidney damage in Type 1 diabetes, and formulating a target for treatment based on the findings.

HbA1c is a blood test which measures average blood sugar levels over the preceding 8 to 10 weeks, and was introduced into diabetes care in the early 1980s. After repeated determinations it is possible to get a measure of the average blood sugar level over many years. The VISS study followed 451 patients, all between the ages of 0 and 34 and suffering from Type 1 diabetes, for over 20 years. It is the first study in the world where blood sugar levels were followed from the very beginning of the illness.

The findings show that no serious eye or kidney damage arose in patients with an average HbA1c value of below 60 mmol/mol (7.6% NGSP). As values rise, the risks rise dramatically: among patients with values over 80 mmol/mol (9.5%), over half had been given laser treatment for serious changes to the eye and one in five had developed serious kidney damage.

The National Board of Health and Welfare currently recommends a target HbA1c value of below 52 which only 17% of Sweden’s over 36,000 patients with Type 1 diabetes achieve (National Diabetes Register). Too low values involve a risk of life-threatening hypoglycaemia. More than half have a value of over 60 mmol/mol. The findings of the VISS study indicate that an HbA1c reading of under 60 is sufficient to avoid serious complications, a target that should be achievable with modern treatment.